Generally, a digital X-ray image detector is a device for detecting radiation passing through the human body in order to obtain desired image information, in which the image information of the radiation is converted into electrical signals, and the converted electrical signals are detected.
According to conventional techniques, such a digital X-ray image detector, which has been developed to overcome various problems of a screen-film system, is composed of an X-ray receptor layer for forming electron-hole pairs by radiation, electrode layers formed on the upper and lower surfaces of the X-ray receptor layer, and a readout unit formed on a physical base substrate of the X-ray receptor layer for converting electrical signals of the X-ray receptor layer into image information.
The conventional digital image detector is classified into a direct type and an indirect type, depending on the manner of converting the X-rays into the electrical signals.
The conventional direct type digital X-ray image detector may obtain X-ray image information using only weak X-ray response properties of the X-ray receptor. For this, the X-ray receptor should be formed to be thick, and a high voltage should be applied through electrodes of both ends of the X-ray receptor in order to amplify the response properties. In addition, problems due to the use of harmful material and the difficulty in forming a large area are caused.
On the other hand, the conventional indirect type digital X-ray image detector employs a process of forming a light-receiving device in a unit cell structure constituting a substrate. However, such a detector suffers because it has low yield, the unit cell is difficult to manufacture, and high manufacturing cost is required. Further, the X-ray receptor is formed merely of a phosphor layer, thereby obtaining low signal detection and poor image quality and not benefiting from the direct response properties of X-rays.